The background description provided herein is for the purpose of generally presenting the context of the disclosure. Work of the presently named inventors, to the extent it is described in this background section, as well as aspects of the description that may not otherwise qualify as prior art at the time of filing, are neither expressly nor impliedly admitted as prior art against the present disclosure.
Digital maps are often generated by assembling a set of map tiles (e.g. 256 by 256 pixel images). The content of the map tiles can include shading, colors, roads, navigation routes, label, markers, building footprints, etc. in either raster, vector, or combined image formats. Upon receiving a geographic query or other input from a user, a mapping application identifies relevant map tiles needed to assemble a digital map and requests the necessary map tiles from a server (i.e. the mapping application “fetches” the map tiles).
Currently, a browser or a mapping application fetches every map tile separately via individual hypertext transfer protocol (HTTP) requests for each rectangular portion of a digital map displayed in a map viewport. However, a typical browser can only have a limited number of concurrently outstanding HTTP requests. Moreover, sending out a request for each map tile adds a significant amount of communication overhead to the transmission of map data.